The only difference is the material! The Classic is made of rigid, white plastic; whereas the Syn is coated in a softer silicone finish. If your boyfriend has some issues with using an enema before using the Aneros, you may want to go for the Classic because the Syn requires a super clean rectum (or else it will hold a stench on it for a while). Also, you have to take greater care of the Syn model, using only water based lube. The Syn is great for comfort, it will feel softer while inserted. Also, it looks pretty -which is always a plus.

i have used extra virgin olive oil with my eupho syn, no perceivable problems. Though i have since switched to shea butter, way better, i highly recommend the shea over anything else. Its delicious feeling :D

@Aneros2 I thought the Syn version had a more tapered tip for easier insertion too? At least that's what I remember reading. From the pics I've seen it looks like the Syn version has a thinner, more streamlined stem. Seems like it gives more natural movement. And I know the P-tab is more flexible than the classic version.

Aneros2, I thought you could use oil-based lube on it too? water-based lube don't agree with me. What about pure aloe Vera?

So despite the common "knowledge", it`s a misconseption that aloe vera hydrates your skin. In fact, it does somewhat of the opposite. One thing it does do though is cool the skin and it`s a good allaround herbal remedy.

I would guess that the reason you can't use water-based lubes, is because most water-based lubes contain glycerin, and it usually causes gastrointestinal distress (i.e., powerful bowel movements). Slippery Stuff Gel was designed for anal use; give it a try - it's relatively cheap online.